Easy to understand step by step guide on how to test an automotive battery without
tools or meters, this information pertains to most vehicles.
Difficulty Scale: 1 of 10
Begin with your vehicle on level ground, parking brake "ON", engine "OFF". Always
wear protective eye wear, gloves and necessary clothing before work begins, stand
clear of the battery while the engine is cranked over.
WARNING - A battery is filled with acid that produce explosive
gasses which can ignite when a spark or flame is present. A battery could have residual
acid on the outside casing, use caution when handling, use baking soda to neutralize
any acid residue before work begins, never connect anything across battery terminals
to create a short, this can cause the battery to explode. Never disconnect a battery
when the engine is running, this can cause electrical system and computer damage.
- Locate and inspect the battery to ensure
a proper connection absent of corrosion. Visit -
Battery Cable Cleaning
Step 2 - Turn the headlights to the "ON" position,
wait 15 minutes, the battery must withstand this load test which simulates the engine
being cranked over by the starter motor.
Battery Terminal Corrosion
Step 3 - Next,
crank the engine over while observing the headlight brightness, they should only
dim slightly when using the starter, if they dim way down, or go out followed by
a machine gun style of clicking noise, the battery can not supply the voltage needed
to operate correctly and must be replaced.
As a battery ages it loses the ability to store electrical energy resulting in
an insufficient flow to the starter. When a starter is subjected to low voltage/amperage
(flow) it will cause the starter to engage and disengage rapidly producing the machine
gun like sound.
A battery will not perform as it should if the alternator has failed, or the
battery has failed internally and replacement is required. Visit -
When a battery short circuits internally, the case sides can bulge indicating
warped plates which short circuit causing the engine to stall due to a drop in system
Battery acid and electrolysis can cause corrosion inside the battery cables which
will inhibit the electrical flow, look for bulges near the top of the cable, these
bulges indicate corrosion expansion caused by the chemical reaction between the
acid and copper wire and must be replaced.
A regular battery must have a "rest" or "down" time to allow the plates inside
time to cool. A battery subjected to constant charge and complete discharge will
fail prematurely unless its a "deep cycle" type. A battery is hazardous material
and must be disposed of at a local parts store or recycle center.
- Battery fails due to age or internal defect
- Battery cables become loose, causing the electrical system to fail and the
engine to stall
Article first published 2016-02-03